//========================================================================
// EventManagerImpl.cpp : implementation side of the event system
//
// Part of the GameCode4 Application
//
// GameCode4 is the sample application that encapsulates much of the source code
// discussed in "Game Coding Complete - 4th Edition" by Mike McShaffry and David
// "Rez" Graham, published by Charles River Media. 
// ISBN-10: 1133776574 | ISBN-13: 978-1133776574
//
// If this source code has found it's way to you, and you think it has helped you
// in any way, do the authors a favor and buy a new copy of the book - there are 
// detailed explanations in it that compliment this code well. Buy a copy at Amazon.com
// by clicking here: 
//    http://www.amazon.com/gp/product/1133776574/ref=olp_product_details?ie=UTF8&me=&seller=
//
// There's a companion web site at http://www.mcshaffry.com/GameCode/
// 
// The source code is managed and maintained through Google Code: 
//    http://code.google.com/p/gamecode4/
//
// (c) Copyright 2012 Michael L. McShaffry and David Graham
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser GPL v3
// as published by the Free Software Foundation.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See 
// http://www.gnu.org/licenses/lgpl-3.0.txt for more details.
//
// You should have received a copy of the GNU Lesser GPL v3
// along with this program; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
//
//========================================================================

#include "../Unix/GameCodeStd.h"
#include "EventManagerImpl.h"
#include "../Utilities/String.h"

#include <SDL3/SDL.h>

//---------------------------------------------------------------------------------------------------------------------
// EventManager::EventManager
//---------------------------------------------------------------------------------------------------------------------
EventManager::EventManager(const char* pName, bool setAsGlobal)
	: IEventManager(pName, setAsGlobal)
{
	m_activeQueue = 0;
}


//---------------------------------------------------------------------------------------------------------------------
// EventManager::~EventManager
//---------------------------------------------------------------------------------------------------------------------
EventManager::~EventManager()
{
	//
}


//---------------------------------------------------------------------------------------------------------------------
// EventManager::VAddListener
//---------------------------------------------------------------------------------------------------------------------
bool EventManager::VAddListener(const EventListenerDelegate& eventDelegate, const EventType& type)
{
	GCC_LOG("Events", "Attempting to add delegate function for event type: " + ToStr(type, 16));

	EventListenerList& eventListenerList = m_eventListeners[type]; // this will find or create the entry;
	for (auto it = eventListenerList.begin(); it != eventListenerList.end(); ++it)
	{
		if (eventDelegate == (*it))
		{
			GCC_WARNING("Attempting to double-register a delegate");
			return false;
		}
	}

	eventListenerList.push_back(eventDelegate);
	GCC_LOG("Events", "Successfully added delegate for event type: " + ToStr(type, 16));

	return true;
}

//---------------------------------------------------------------------------------------------------------------------
// EventManager::VRemoveListener
//---------------------------------------------------------------------------------------------------------------------
bool EventManager::VRemoveListener(const EventListenerDelegate& eventDelegate, const EventType& type)
{
	GCC_LOG("Events", "Attempting to remove delegate function from event type: " + ToStr(type, 16));
	bool success = false;

	auto findIt = m_eventListeners.find(type);
	if (findIt != m_eventListeners.end())
	{
		EventListenerList& listeners = findIt->second;
		for (auto it = listeners.begin(); it != listeners.end(); ++it)
		{
			if (eventDelegate == (*it))
			{
				listeners.erase(it);
				GCC_LOG("Events", "Successfully removed delegate function from event type: " + ToStr(type, 16));
				success = true;
				break;  // we don't need to continue because it should be impossible for the same delegate function to be registered for the same event more than once
			}
		}
	}

	return success;
}


//---------------------------------------------------------------------------------------------------------------------
// EventManager::VTrigger
//---------------------------------------------------------------------------------------------------------------------
bool EventManager::VTriggerEvent(const IEventDataPtr& pEvent) const
{
	GCC_LOG("Events", "Attempting to trigger event " + std::string(pEvent->GetName()));
	bool processed = false;

	auto findIt = m_eventListeners.find(pEvent->VGetEventType());
	if (findIt != m_eventListeners.end())
	{		
		const EventListenerList& eventListenerList = findIt->second;
		for (EventListenerList::const_iterator it = eventListenerList.begin(); it != eventListenerList.end(); ++it)
		{
			EventListenerDelegate listener = (*it);
			GCC_LOG("Events", "Sending Event " + std::string(pEvent->GetName()) + " to delegate.");
			listener(pEvent); // call the delegate
			processed = true;
		}
	}
	return processed;
}


//---------------------------------------------------------------------------------------------------------------------
// EventManager::VQueueEvent
//---------------------------------------------------------------------------------------------------------------------
bool EventManager::VQueueEvent(const IEventDataPtr& pEvent)
{
	GCC_ASSERT(m_activeQueue >= 0);
	GCC_ASSERT(m_activeQueue < EVENTMANAGER_NUM_QUEUES);

	// make sure the event is valid
	if (!pEvent)
	{
		GCC_ERROR("Invalid event in VQueueEvent()");
		return false;
	}

	GCC_LOG("Events", "Attempting to queue event: " + std::string(pEvent->GetName()));
	auto findIt = m_eventListeners.find(pEvent->VGetEventType());
	if (findIt != m_eventListeners.end())
	{
		m_queues[m_activeQueue].push_back(pEvent);
		GCC_LOG("Events", "Successfully queued event: " + std::string(pEvent->GetName()));
		return true;
	}
	else
	{
		GCC_LOG("Events", "Skipping event since there are no delegates registered to receive it: " + std::string(pEvent->GetName()));
		return false;
	}
}

//---------------------------------------------------------------------------------------------------------------------
// EventManager::VTick
//---------------------------------------------------------------------------------------------------------------------
bool EventManager::VUpdate(unsigned long maxMillis)
{
	unsigned long currMs = SDL_GetTicks();
	unsigned long maxMs = ((maxMillis == IEventManager::kINFINITE) ? (IEventManager::kINFINITE) : (currMs + maxMillis));

	// This section added to handle events from other threads.  Check out Chapter 20.
	// IEventDataPtr pRealtimeEvent;
	// while (m_realtimeEventQueue.try_pop(pRealtimeEvent))
	// {
	// 	VQueueEvent(pRealtimeEvent);

	// 	currMs = SDL_GetTicks();
	// 	if (maxMillis != IEventManager::kInfinite)
	// 	{
	// 		if (currMs >= maxMs)
	// 		{
	// 			GCC_ERROR("A realtime process is spamming the event manager");
	// 		}
	// 	}
	// }

	// swap active queues and clear the new queue after the swap
	int queueToProcess = m_activeQueue;
	m_activeQueue = (m_activeQueue + 1) % EVENTMANAGER_NUM_QUEUES;
	m_queues[m_activeQueue].clear();

	GCC_LOG("EventLoop", "Processing Event Queue " + ToStr(queueToProcess) + "; " + ToStr((unsigned long)m_queues[queueToProcess].size()) + " events to process");

	// process the queue
	while (!m_queues[queueToProcess].empty())
	{
		// pop the front of the queue
		IEventDataPtr pEvent = m_queues[queueToProcess].front();
		m_queues[queueToProcess].pop_front();
		GCC_LOG("EventLoop", "\t\tProcessing Event " + std::string(pEvent->GetName()));

		const EventType& eventType = pEvent->VGetEventType();

		// find all the delegate functions registered for this event
		auto findIt = m_eventListeners.find(eventType);
		if (findIt != m_eventListeners.end())
		{
			const EventListenerList& eventListeners = findIt->second;
            GCC_LOG("EventLoop", "\t\tFound " + ToStr((unsigned long)eventListeners.size()) + " delegates");

            // call each listener
			for (auto it = eventListeners.begin(); it != eventListeners.end(); ++it)
			{
                EventListenerDelegate listener = (*it);
                GCC_LOG("EventLoop", "\t\tSending event " + std::string(pEvent->GetName()) + " to delegate");
				listener(pEvent);
			}
		}

		// check to see if time ran out
		currMs = SDL_GetTicks();
		if (maxMillis != IEventManager::kINFINITE && currMs >= maxMs)
		{
			GCC_LOG("EventLoop", "Aborting event processing; time ran out");
			break;
		}
	}

	// If we couldn't process all of the events, push the remaining events to the new active queue.
	// Note: To preserve sequencing, go back-to-front inserting them at the head of the active queue
	bool queueFlushed = (m_queues[queueToProcess].empty());
	if (!queueFlushed)
	{
		while (!m_queues[queueToProcess].empty())
		{
			IEventDataPtr pEvent = m_queues[queueToProcess].back();
			m_queues[queueToProcess].pop_back();
			m_queues[m_activeQueue].push_front(pEvent);
		}
	}

	return queueFlushed;
}